Light emitting diodes are semiconductor light emitting devices which convert electrical energy to light energy. LEDs, like ordinary diodes, includes a p-n junction, and emit light using semiconductor as a light emitting material. Holes from a p-region and electrons from an n-region combine in semiconductor material, such that excess energy is released and photons are emitted. Because different semiconductor materials have different bandgaps and holes and electrons have different energy states, different energy is released while holes and electrons are combined. Therefore, lights having different wavelengths can be produced.
With advancement of technology, performance of LED is increased, and LEDs are widely used in different fields, such as lighting, decoration, backlight source, and landscape lighting. However, some challenges are faced due to such fast development of LEDs. First, since the era of low carbon economy is coming, it is necessary to develop LEDs that are more economical. Secondly, since LEDs are rigid and are not pliable and LEDs cannot be used in some applications, it is required to develop flexible LEDs.
For achieving flexibility of LEDs, OLEDs are currently adopted because they have excellent flexibility. However, process conditions for producing OLED are strict, and it is difficult to manufacture large sized displays. On the other hand, conventional inorganic semiconductor LEDs still have the problem that semiconductor silicon material thereof is too rigid, in particular under the circumstance when the displays have to be bended.